drm/amdgpu: clean up some inconsistent indenting

Eliminate the follow smatch warning:

drivers/gpu/drm/amd/amdgpu/nbio_v7_7.c:35 nbio_v7_7_get_rev_id() warn:
inconsistent indenting.

drivers/gpu/drm/amd/amdgpu/nbio_v7_7.c:214 nbio_v7_7_init_registers()
warn: inconsistent indenting.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>